MRI/CT guided multiregional ‘smart’ biopsy in sarcomas: a prospective development study

Abstract Background Intratumoral heterogeneity means single site tumor biopsy might not be representative, leading to erroneous conclusions about tumor biology and therapy selection. Here we develop and optimize an MRI-informed multiregional biopsy technique in retroperitoneal and pelvic sarcomas (RPS). Methods Participants with suspected RPS underwent multiparametric (mp)MRI within a week prior to biopsy. Three ‘target regions’ with differing imaging characteristics were contoured. Robotic or freehand multiregional CT-guided biopsy (n = 6 each) was performed between September 2021 and September 2022, collecting samples separate specimen pots for each target region. CT/MRI fusion extracted quantitative imaging biomarkers at precise biopsy sites for correlation with histological biomarkers. The primary endpoint was safety and feasibility. Spearman's correlation was performed for imaging/histological biomarkers. Results Twelve participants (7 women), median age 58.6 years interquartile range [IQR]: 52–75 years underwent biopsy. All procedures were technically successful with same-day discharge and no complications. While absolute values of ADC and %Ki-67 did not correlate (Spearman’s ρ = -0.08), we observed a very strong correlation between the range of ADC values and the range of Ki-67 proliferation index values across biopsy sites; Spearman’s ρ = 0.93 (95% CI 0.74 to 0.98). Ranges, which represent intratumoral heterogeneity, can only be obtained using multiregional biopsy. Conclusions Multiregional MRI-informed, CT-guided biopsy is feasible and can be safely carried out using freehand and robotic guidance. Sampling three distinct regions within tumors provides a more comprehensive and accurate representation of tumor biology compared to conventional single-site biopsy. Ethical approval A phase I/IIa institutional review board approved prospective development study, identifier 1102, 17/06/2021.